The Glacial Lake Souris occupied the basin of the Souris River from the most southern portion of this river's loop in North Dakota to its elbow in Manitoba, where it turned sharply northward and passed through the Tiger Hills. The length of Lake Souris was about 170 miles, from latitude 48° to latitude 50°35', and its maximum width, north of Turtle Mountain, was nearly 70 miles. It was situated near the far southeast corner of the large glacial Lake Agassiz, separated from it by another small glacial body, Glacial Lake Hind.